RECEPTORS #1

1.)Receptors are SPECIFIC- they only detect SPECIFIC STIMULUS. Some receptors are cells and some are proteins on cell surface membranes.

How do receptor cells that communicate via the nervous system work?

-When a nervous system receptor is in its RESTING STATE, theres a differece in voltage between the inside and outside of the cell- this is generated by ion pumps and ion channels. The difference in voltage across the membrane is called the POTENTIAL DIFFERENCE.

-The POTENTIAL DIFFERENCE when a cell is at rest is called its RESTING POTENTIAL. When a stimulus is detected, the cell membrane is EXCITED and becomes MORE PERMEABLE. This allows MORE IONS to MOVE IN AND OUT of the cell- altering the POTENTIAL DIFFERENCE. The change in potential difference due to a stimulus is called the GENERATOR POTENTIAL.

-A BIGGER STIMULUS excites the membrane more, causing a BIGGER MOVEMENT of IONS and a BIGGER CHANGE in potential difference-so a BIGGER GENERATOR POTENTIAL is produced.

-If the generator potential is BIG ENOUGH it'll trigger an ACTION POTENTIAL- an electrical impulse along a NEURONE. An action…